Displacement of anterior cerebral vessels in cerebral dynamic study in cases of chronic subdural hematomas.
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About 75-80% chronic subdural hematomas give positive results in a brain scan. The typical scintigraphic finding of chronic subdural hematoma is a diffuse widening and increase of the peripheral activity on the anterior view. In the flow studies subdural hematomas lead occasionally to peripheral activity defects. In two cases of chronic subdural hematoma without typical patterns in a perfusion study as well as in static images, we found a displacement of the anterior cerebral vessels as an indircet sign of space occupation. (+info)
Sinusitis demonstrated by brain scanning.
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Increased concentration of technietum was noted in the region of the frontal, ethmoidal, and maxillary sinuses of two patients. Radiographs of the sinuses revealed extensive sinusitis involving the sinuses in the area of increased uptake. The increased uptake was attributed to the sinusitis. (+info)
Increased uptake of 99mTc-sulfur colloid in vertebral compression fractures.
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Increased uptake of 99mTc-sulfur colloid in vertebral bodies of two patients with vertebral compression fractures was noted on a liver-spleen scan. This finding has not previously been reported in the literature. The mechanism of localization of 99mTc-sulfur colloid in bone marrow depends on regional blood flow and increased reticuloendothelial and phagocytic cell activity. Both mechanisms are felt to be involved in these cases. In fractures, hyperemia and phagocytic activity are transient phenomena and therefore the above observations may be useful in determining fracture age. (+info)
High temporal resolution ECG-gated scintigraphic angiocardiography.
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The cardiac blood pool is visualized with high temporal resolution during a complete, average, cardiac cycle. The technique yields both qualitative and quantitative measures of cardiac performance. (+info)
Pharmacokinetics of radioiodinated streptokinase.
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The pharmacokinetics of radioiodinated streptokinase have been investigated in mice and dogs in order to explore further its potential usefulness as a radiopharmaceutical to detect thrombi and neoplasms. The purified streptokinase used in these studies showed no alteration in its physical or enzymatic properties following radioiodination. In the mouse, radioiodinated streptokinase accumulated rapidly in the liver and at 4 hr, large amounts of free iodine were detected in the plasma. The plasma clearance curve in dogs was biexponential showing that 70% of the protein-bound radioactivity was cleared with a half-life of 1525 min while the remaining 30% was cleared with a half-life of 6080 min. Seventy percent of the plasma radioactivity appeared as free iodine after 4 hr. No change in clearance was obtained by preloading animals with unlabeled streptokinase. Based primarily on the rapid plasma clearance, deiodination, and possible limitations of effectiveness of preloading with unlabeled streptokinase, the results of these studies are in accord with the conclusion that radioiodinated streptokinase may have restricted usefulness as a radiopharmaceutical for detecting thrombi and neoplasms. The full extent of its potential usefulness, however, awaits the provision of further in vivo and in vitro studies directed at testing a covalently modified enzyme that retains streptokinase activity but whose immunologic properties have been altered so that the enzyme is not as rapidly cleared from the plasma. (+info)
Production and characteristics of 125Xe: a new noble gas for in vivo studies.
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Radionuclides of the noble gases are extensively used to assess ventilation and blood flow in clinical and investigative studies. Xenon-133 is most commonly used but is not optimal for these in vivo studies. Xenon-125 has better physical characteristics and can be produced with a cyclotron by a 127I(p,3n)125Xe reaction; this reaction results in a maximum of 25 mCi/gm/cm2/muA-hr for 31-MeV protons. Under actual production conditions, 11 mCi/muA-hr were collected. Xenon-125 decays by electron capture with a 17.2-hr half-life and contributes less radiation per dose of radioactivity than 133Xe. The radiation dose to the lungs from 133Xe and 125Xe is 5.0 and 1.8 mrads/mCi-min, respectively. The radiation dose per usable photon for 125Xe is only 0.3 of 133Xe. The principal photons of 125Xe, 188 keV (55%) and 243 keV (29%), are more intense and are in an energy range that is more advantageous for imaging than the 81 keV (35%) of 133Xe. These physical properties of 125Xe result in better spatial resolution at the same information density and with less radioactivity administered to the patient. Phantom studies showed that 12.7-, 9.5-, and 6.4-mm lead bars were resolved with 125Xe using a 410- keV diverging collimator wheras only the 12.7- and 9.k-mm lead bars were resolved using 133Xe and either a 410-keV or 140keV diverging collimator. (+info)
Gallium gallbladder scanning in cholecystitis.
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Gallium has been shown to accumulate in metabolically active tissue including sites of infection. The purpose of this study was to evaluate gallium scanning in cholecystitis. Ten patients with cholecystitis were studied using conventional gallium scanning techniques. Five patients with acute cholecystitis showed intense gallium accumulation in the gallbladder area. One of five patients with chronic cholecystitis showed significant accumulation in the gallbladder. The limitations of this method are mainly the need for serial scanning to rule out gallium accumulation in the hepatic flexure of the colon and also the failure to detect consistently a chronically diseased fibrotic gallbladder. We conclude that gallium scanning of the gallbladder is an important adjunctive study in the evaluation of cholecystitis. (+info)
Thallium-201 for medical use. I.
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Thallium-201 merits evaluation for myocardial visualization, kidney studies, and tumor diagnosis because of its physical and biologic properties. A method is described for preparation of this radiopharmaceutical for human use. A critical evaluation of 201Tl and other radiopharmaceuticals for myocardial visualization is given. (+info)